Hydraulic press



Jan. 31, 1933. w. ERNST ET AL 1,895,710

HYDRAULIC PRESS Filed NQv. 24, 1931 2 Sheets-Sheet l Jan.31`,1933.WERNST'ET AL y 1,895,110

HYDRAULF C PRES S Filed NOV. 24, 1931 2 sheets-sheet 2 A ILV/l/IlIIIlllllIll/llllllll/ n! fi/@n Gttornegs.

Patented Jan. 31, 1933 UNITED STATES.

WALTER ERNST -`ANI) HOWARD F. MACMILLIN, OF MOUNT GILEAD, OHIO,ASSIGNORS TO THE HYDRAULIO'PRESS MFG. CO., 0F MOUNT GILEAD, OHIOHYDRAULIc Pimss Application led November 24, 1931.

This invention relates to hydraulic presses and more particularly tohydraulic press operating circuits.

In order to attain high operating speeds in reciprocating pressesderiving their power from iiuid under pressure it is common to providecylinders and cooperating rams for positively driving the press platenor other re-` ciprocatory element in both directions, and in many casesto provide both main pressing and auxiliary or booster cylinders andrams of relatively small diameter so that, for a given rate of fluidsupply, the reciprocatory press element will be advanced rapidly towardthe work during the initial part of a pressing stroke and prior toengagement with the work. In such presses it is desirable to employ whatis usually termed a surge valve which controls communication between themain press cylinder and the circuit reservoir and which provides for theprefilling of the main cylinder `when the press rams are being movedtowards the work under the action of the booster rams. It is necessarythat means be provided for positively holding the surge valve openduring a return stroke so as to permit the fluid contained in the maincylinder to be readily discharged directly to the surge tank orreservoir.

An object of the present invention is toprovide a simplified pressoperating circuit of the general character referred to above, includinga surge valve and a novel devicevfor operating the valve. Amore'specific object is to provide such a press circuit in which thepump discharge is constantly directed to the push back or ram-returningchamber. Other objects will become apparent from a reading of thefollowing description, the appended clainls, and the accompanyingdrawings, in Whic Figure 1 is a front view of a press withy elementthereof being shown in the position occupied during a pressing stroke;and

Figures 3 and 4 are views similar to Figure Serial No. 577,142.

' connected to the base by means of. strain rods 3, and a platen 4guided on the strain rods for reciprocatory movements towards and awayfrom the base. For reciprocating the platen,

-the press is provided with cylinder means including a main cylinder 5defining a main pressing chamber 6 and auxiliary cylinders 7 7, theupper ends of which dei-ine booster `chambers 8 8 and the lower ends ofwhich define ram-returning chambers 9 9. A main ram 10 is connected tothe platen and is mounted for reciprocation in the main pressing chamber6 and auxiliary rams 11 11 are mount-ed for reciprocation in therespective cylinders 7 7 these auxiliary rams being connected to theplaten by means of rods or extensions 12 12.

The press operating circuit includes a surge 4 tank or reservoir Bmounted directly on top of the main cylinder 5 of the press, asupplementary tank or reservoir B', a pump C, and hydraulic connectionsforming a circuit with the respective chambers of the press, the tanks,and the pump. These connections include a surge valve D, a control valveE, and

suitable piping. The piping includes a pump suction pipe 13 beingconnected at one of lts ends to the intakeside of the pump and at itsother end communicating with intake lor suction branches 14 and 15 whichrespectively communicate with the tanks B and B. A pump discharge pipe16 communicates at one of its ends with the discharge side of the pumpand at its other end with the control valve E. A pipe 17 alsovcommunicates at one of its ends with the discharge side of the pump andat its other end communicates with the ram-returning chambers 9 of theauxiliary cylinders. A delivery pipe 18 communicates at one of its endswith the control valve E and at its upper end i with the boostervfilling of the main pressing chamber during the initial part of'apressing stroke and for the exhausting of the pressing chamberv during areturn stroke. This valve includes a casing or cage 21 which extendsthrough an opening 22 in the upper end of the main cylinder and which isformed with a top pe.

ripheral .ange23 which fits within a counter-bore 24 in the top of thecylinder. A movable valve element 25 is mounted within the cage 21 andis provided with spaced vertically extending ribs 26 which slidev withinareduced bore 27 in the cage. The element 25 is formed at its lower endwith an enlarged v part 28 which slideswithin an enlarged bore 29 at thelower end of the cage, and is formed i with a tal ered seat-engagingsurface`30 intervening etw'een the upper reduced and the lower enlargedportions of the valve element. This tapered surface is adapted'to engagea correspondingly tapered seat 31 formed at the bottom of the, reducedbore 27 in the cage. Just below the tapered-seat 31 the cage is formedwith a plurality of portsl 32 providing communication between the insideof the cage and the main pressing chamber. A

biasing spring 33 is interposed between the valve element 25 and an endplate 34 secured in the bottom end of the cage, this spring servingnormally to maintain the element in closed position. The surge valve asso far described is similar to the surge valve shown, described, andclaimed in the application of Walter Ernst, Serial No. 501,994, filedDemember-12, 1930, and does not per se constitute the present invention.

A frame member 35 is mounted on top of the cylinder 5, being clampeddown against the surge valve cage by means of bolts'36, thus serving tomaintain the valve cage in place. This frame member is formed with"aplurality of ports 37 which provide communicationbetween the interiorof the valve cage and the surge tank B; The frame is provided with anupwardly extended portion providing a cylinder 38 formed with a bore 39disposed coaxially with the valve cage 21.

Mounted in the cylinder 38 is a differential hydraulic plunger 40comprising a head 41 slidable within the bore 39, a small stem extendingfrom the head downwardly through an opening in the frame to apoin't justabove the valve element- 25, and a large stem 43 extendingupwardly 4fromthe head 41 through a cylinder end plate or collar 44.

In accordance with the invention, the differential plunger has itsopposite sides respectively exposed to pressure in the ram-returningchambers and the booster chambers, and in order to efect this conditiona branch pipe 45 isinterposed between the pipe 17 and the upper end ofthe cylinder bore 39, and a branch pipe 46 is interposed between thedelivery pipe 18 andthe lower end of the bore- 39 of the cylinder 38,the arrangement as,

'shown beingsuch that the upper or smaller 'ns'I area of the head 41 isconstantly exposed to y the pressure existing in the ram-returningchambers while the lower and larger area of the4 head 41 is constantlyexposed to the pressure existing in the booster chambers.

The control valve E includes a casing47 formed with a central bore 48closed at its endsby discs 4 9 and 50 respectively posi-l tioned incounter bores 51 and 51a anda movable piston valve element 52 mountedfor sliding movements within the bore 48.

53, 54, and 55, a reduced portion56 interposed-between and connectingthe heads 53v and 54, a reduced portion-57 interposed be-l tween andconnecting the heads 54 and 55,

heads 53and 55, and a branch passage 66a is formed in the piston valveforv providing communication ybetween the passagel 66 andv the spaceintervening between the heads 54 and 55.

The valve casing is formed with a passage 67 which connects the extremeend .portions of the valve chamber, or bore 48, and a short passage 68formed within the valve casing provides constantv communication betweenthe passage 67 and an annular enlarged part 69 of the bore 48.v Thevalve casing is threaded to receive the exhaust pipe 20 at a pointadjacent the intersection of the passages 67 and 68, so that thesepassages always com- The'` piston valve 52 comprises three spaced heads-municate with'the exhaust pipe 20 and cond.,120 ,sequently with thereservoirs B andvB.

vThe valve casing is also formednear its `vleft hand end as viewed inFigures 2,-3, and

Cates with an annular enlarged part 7'1v of the bore 48, the casingbeing threaded at the munication between the respective pipes.

` predetermined extent.

In the'position shown in Figure 2, the fluid entering through the pumpdischarge pipe 16 will flow first through the inlet port 70, thenthrough the enlarged bore 71, then through that part of the bore 48included between the heads 53 and 54, then through the enlarged bore 72, and then through the outlet port 73 into the delivery pipe 18. Therewill be no iow of fluid through the exhaust pipe 20 -When the valve isin this position,

since communication of the passages 67 and 68 is cut off from the pipes16 and 18 by means of the head 55 and the head 53 respectively.

When the valve is in the position shown in Figure 3,'the head 55 willcut o-i' flow of fiuid through the pump discharge pipe 16 and the pipe18 will communicate with the exhaust pipe 2() by means of the inlet port73, the enlargedbore 72, that part of the bore 48 included between thehead 54 and the head 53, the enlarged bore 69, and the lpassage 68.

When the valve is in the position shown in Figure 4, fluid enteringthrough the pump discharge pipe 16 will fiow through the pas'- sage 70,the enlarged bore part 71, the passages 66a and 66 within the valveelement 52, that part of the bore 48 included between the head 53 andthe disc 49, the passage 67, and through the passage 68 into the exhaustpipe 2O and thence tov the tank B. At this time the delivery pipe 18will communicate with the exhaust pipe 20 by means of the passage 73,the enlarged bore part 72, that part of the bore 48 included between theheads 53 and 54, and the passage 68.

It is desirable that, when the valve 52 is in its Figure 2 position,communication be established between the pipes 18 and 19 when thepressure in the pipe 18 has built up to a To this end the valve casing47 is provided with an upper extension or enlargement formed with a bore74 traversing and intersecting the auxiliary port 73, there being formedat its left hand end an enlarged part or annular depression 75. Aplunger valve 76 is mounted for sliding movements within the bore 74 andis provided with ahead 77 arranged to slide within an enlarged bore 78coaxial with the bore 74. A spring 79 is interposed between the head 77and a threaded plug 80 which closes the left hand end of the bore 78,this spring serving normally to maintain-the valve 76 in its closedposition, a iange 81 intervening between the b ores74 and 78 serving tolimit the movement of the valve to the right. A plug 82 serves to closethe right hand end of the bore 74. A port 83 provides constantcommunication between the enlarged bore and the branch delivery pipe 19which is connected to the casing at the upper end of the port 83. Inoperation, when pressure builds up in the pipe 18 and consequently inthe bore 74 to a point dependent upon the force exerted by the spring79, the .valve 76 will be moved to the left so as to affordcommunication between` the bore 74 and the enlarged bore 75,consequently'providing communication between the pipe 18 and the pipe19.

It is desirable that, when the platen reaches a predetermined positionduring an upward or return stroke, the valve 52 be moved to its Figure 4position. To accomplish this purpose, we have provided platen-operatedmeans comprising a rod 84 mounted for vertical sliding movements inguides 85 and 86 respectively carried by one of the auxiliarycylinders'7 and the press base 1, the rod 84 extending through and beinglslidable relative to a boss4 87 on the end .pf an arm 88 connected tothe platen. A collar 89 secured to the upper end of the rod 84 isengageable with the guide 85 for limiting downward movement of the rod,and a collar 90 secured to the rod in adjusted position is adapted to beengaged by the boss 87 when the platen reaches a predetermined pointduring its upward travel for raising the rod to move the valve to itsFigure 4 position l 'through the medium of connections interposedbetween the rod and valve. These connections include a collar 91 securedto the rod adjacent the lower end thereof and being adapted lwhen.raised to engage the round head 92 of one arm of the bell crank lever93 pivoted'as at 94 to a bracket 95 for rocking the bell crank in aclockwise direction, the other arm 96 of the bell crank lever beingconnected lto the clevis 65 on the valve stem 62 by means' of a' pin andslot connection 97. rIfhus, when the .rod 83 is raised by engagement ofthe boss 87 with the collar 90. the collar 91 will engage the round head92 of the bell crank lever, thereby rocking the latter in a clockwisedirection and moving the the platen and rams are in their upperposiexhaust pipe 20 and tank B in the manner already described. The pipe16 will have restricted communication withthe exhaust pipe 20 bymeans ofthe inlet passage 70, Ythe enlarged bore 71, the patsages 66a and 66 inrams, the valve 52 is moved from its Figure 4 position to its Figure 2position.- The discharge from the pump will then be directed to thedelivery pipe 18 through the medium of the discharge pipe 16, the inletport 70, that part of the bore v48 intervening between the heads `53 and54, and-the outlet port 73, this'uid being delivered to the boosterchambers 8. At the same time fluid under the same unit pressure will bedelivered throughthe pipe 17 to the ram-returning chambers 9, so thatthe same unit pressures will act on the upper and lower sides of therams 11. However, since the effective pressure areas of the upper sidesof these rams are considerably greater than the effective pressure areasof the lower sides thereof, the total pressure acting on the rams willbe greater on the top sides than the bottom sides, so that the rams willbe moved downwardly. Thiswill` positively move the platen 4 and the mainram 10 downwardly, the movement of the ram 10 tending to createl avacuum in the main pressling cylinder 6 which will result in theopeningpof the surge valve against the pressure of the spring 33, thuspermittingprelling of the pressing chamber 6 from the surge tank B. Whenthe platen encounters resistance to its downward travel, pressure willbuild up in the delivery pipe 18 causingA the valve 76 to open againstthe pressure of the spring 79, thus placing the branch delivery pipe 19in communication with the delivery pipe 18 and with the pump dischargepipe 16. Fluid will then be delivered from the pump to the boosterchambers 8 andito the mainl`v pressing chamber 6, causing a building upof pressure in the latter with consequent closing of the surge valve.The platen will then be moved downwardly under the combined action ofthe booster rains 11 and main ram 10, it being noted that during theentire downward movement of the platen and rams the ram-returningchambers 9 have been in constant communication with the discharge sideof the pump.

When the desired pressure has been exerted upon the work, the pistonvalve v52 will be movedto'its Figure 3 position, in which position ofthe valve communication will be afforded between the delivery pipe 18and the exhaust pipe20 in the manner heretoforedescribed, and at thesame time How of fluid will be returnedto the tanks by means of the pipe18, the control valve E, and the exhaust pipe 20. Since the boosterchambers are in communication with the exhaust at this time, thepressure in the deliverypipe 18 and con` sequently in the branch pipe 46and lower end of the cylinder 38 will be small, so that the pressureacting through the pipe 17 and consequentlyl through the branch pipe 45and in the upper end 01` the cylinder 38 will act upon the smaller areaof the head 41 of the differential plunger 40, thereby moving the latterdownwardly into engagement with the surge valve and opening the latterto permit the free discharge of fluid from the pressing chamber 6 intothe surge tank B, i

When the platen approaches the limit of its upward travel, the boss 87willv engage the colla-r 90 and will lift the 'rod 84 in the mannerpreviously described, thereby rocking the bell crank 93 and moving thepiston valve 52 :from its Figure 3 position to the left. The rams andplaten will continue to ascend until the piston valve 52 has been movedto the left to a position wherein the head 55 will eii'ect just suicientthrottliiig of Huid flow through the valve to the exhaust pipe 20 toproduce enough back pressure to maintam the rams and platen at rest intheir upper positions. This condition will exist when the valve 52 hasbeen moved to its -Figure 4 position, at which time'the rams will bebrought torest, thus completing a single operating c cle.

yIn order to provide for eflicient pre-illing and exhausting of the mainpressing chamber, it is desirable that the surge valve be of large area.For this reason it is often diiicult to open the valve against the highpresssure existing in the main pressing chamber at the end of a pressingstroke, and,` in order to render the opening of the valve more easy andto prevent the occurrence of shocks which would otherwise occur if thevalve were suddenly opened while the iiuid in the main pressing chamberwere under very high pressure, a check valve 98 is interposed betweenthe branch delivery v pipe 19 and the delivery pipe 18, tlie'valve bethe delivery pipe 18 in communication with the exhaust pipe 20, thepressure in the pipe 18 will drop below that in the pipe 19,. and therewill be a limited fiow of fluid from the pipe 19 to the pipe 18 therebyrelieving the pressure in the main pressing chamber 6 so that the surge.valve may be opened easily and without the occurrence of shocks due tothe expansion of the compressed fluid.

' Although the invention has been illustrated herein -as being embodiedin a press constructed for the performance of pressing operations, it isto be understood that the invention may be used in connection withhydraulic machines having reciprocatory rams provided with punches,shears, dies, or other similar tools instead of with a platen of theykind illustrated, and that various other modifications and ch anges maybe madein the construction and arrangement of the parts withoutdeparting from the spirit of the invention as defined in the appendedclaims.

Ve claim: L

1. The combination with a press having cylinder means including a mainpressing chamber, a booster chamber, a ram-returning chamber, andcooperating ram means in said chambers; of a reservoir; a pump; meansforming a hydraulic circuit with said chambers, said reservoir, and saidpump comprising a pipe affording constant communication between saidpump and said ram-returning chamber, a deliveryvpipe adapted to affordcommunication between said pump and said booster chamber, a branch pipeadapted to afford communication between said booster chamber and saidmain pressing chamber,

valve means tor controlling flow of fluid through said delivery pipe andsaid branch pipe and a surge valve independent of said control valvemeans interposed between said main pressing chamber and said reservoirand including a movable element and biasing 'means associated with saidelementfor yield- `ably urging the latter to closed positionhsaidelement being movable to ,open7 position against the urge of saidbiasing means duringthe first part of a pressing stroke by suction insaid main pressing chamber; and a differential plunger associated withsaidsurge valve element for operating the latter and having its oppositesides exposed to pressure in said ram returning and boosterchambersrespectively. Y 2. The combination with a press havin cylinder meansincluding a main pressing chamber, a booster chamber, a ram-returningchamber and cooperating ram means in said chambers; of a reservolr; ,apump; means forming a .hydraulic circuit with said chambers, saidreservoir, and said pump comprising. a pipe affording constantcommunication between saidpump and said ram-returning chamber, adelivery pipe adapted to afford communication between said pump and saidbooster chamber, a branch pipe adapted to afford communicationlbetweensaid booster chamber and said` and saidreservoir and including a movabieelement and biasingI means associated with said element for yieldablyurgin the latter to closed position, said elementI eing movable to openposition against the urge of said biasing means during the first part ofa pressing stroke by suction in said main pressing chamber; and adifferential plunger associated with said surge valve element foroperating the latter and having its opposite sides exposed to pressurein said ram returning andbooster chambers respectively. 3. Thecombination with a press having cylinder means including a main pressingchamber, a booster chamber, a ram-returnin chamber and cooperating rammeans in sai chambers; of a reservoir; a pump; means forming a hydrauliccircuit with said cham-- bers, said reservoir, and said pump comprisinga pipe affording constant communication between said pump and sai-dram-returning chamber, a delivery pipe adapted to aord communicationbetween said pump and said booster chamber, a branch pipe'ada ted toafford communication between said ooster chamber and saidy main pressingchamber,

lvalve means for controlling flow of fluid through said booster pipe andsaid branch pipe, a surge valve independent of said control valve meansinterposed between said main pressing chamber and said reservoir andincluding a movable element and biasing means associated with saidelement' for yieldably urging the latter to closed position, said`element being movable to open position ed in said chambers; of areservoir; a pump; a plpe affordlng constant communlcationfbetween thepump and ram-returning chamber; a discharge pipe connected to the pump;a delivery pipe connected to said booster cham- -posed between saidmainpressing chamber ber; a branch .delivery pipe adaA ted to aordcommunication between said elivery pipe and said main pressing chamber.;a pressure operated valve for controlling said cemmunication; an exhaustpipe communicating -with said reservoir; a control valve interinterposedbetween said main pressing chamf to open position against the urge ofsaielber and said reservoir and includingamovable element and biasingmeans associated with said element for yieldably urging the latter toclosed position, said element being movable biasing means during the rstpart of a pressing stroke by suction in said main pressing chamber; anda dii'erential plunger associated with said surge valve element foroperating the latter and having its opposite sides vexposed to pressurein said ram returning .l vand booster chambers respectively.

5. The combination with a press having cylinder m'eans including a mainpressing chamber, a booster chamber, a ram-returning chamber, andcooperating ram means mounted in said chambers; of a reservoir; a' pump;

a pipe aiiording constant communication between the pump andram-returning chamber; a discharge pipe connectedto the pump; a

. delivery pipe connected to said booster champipe, then to cut of flowof iuid through said A ber; a: branch delivery pipe adapted to affordcommunication betw'een said delivery pipe and said mainl pressingchamber; a pressure operated valve for controlling said communi'cation;an exhaust pipe communicating with said reservoir;a control valveinterposed between said discharge pipe, said delivery pipe, and saidexhaust pipe and including a casing provided with ports and a valveelement movable to open and close said ports., said element beingmovable to three positions first to aiord communication between saiddischarge pipe and said delivery discharge pipe, and then to providefora throttled ow from said discharge pipe to said exhaust pipe; ramoperated means for moving said element from its second to its thirdposition at the end of a return stroke whereby said pump willv operateagainst suf- 1 icient back pressure to sustain the weight of said rammeans; a surge valve interposed between said main ressin chamber andsaid reservoir; and a differential hydraulic plung- .er associated withsaidl sur e .valve for operating the .latter and' having its oppositesides respectively exposed to pressure in said subscribed our names.

ram-returning chamber and in said booster chamber.

In testimonyy whereof, we have hereunto WALTER ERNST. l:.70

HOWARD F. MecMILLIN.

